V 4 in snowmobile

[ClutchMaster]

It is the extremely high RPM that has an effect on valve train operation. Explained in attached article.
https://www.cycleworld.com/story/motorcycle-racing/2020-bmw-m-grand-prix-of-styria/

https://www.motorsportmagazine.com/...togp/why-are-motogp-v4s-faster-than-inline-4s

Interesting, not a lot of details tho. The inline bikes have two extra main bearings, so a tad more parasitic drag but capable of more horsepower when power adders are used. I can see less Gyroscopic forces helping MotoGP bikes turn quickly being a factor.

Quoted from the article I posted....
“allows designers to use a greater variety of unbalanced firing orders – big bang, long bang and so on”

^^^^^^^this is a bunch of bunk, don’t believe everything you read!

 

[ClutchMaster]

I’m not so sure that crankshaft vibrations can cause valve train issues....but I am positive that the springless mechanical valve actuation used by Ducati will allow a much more aggressive camshaft profile and ultra high rpm without valve float.

https://en.m.wikipedia.org/wiki/Desmodromic_valve

I knew it had to be something different in the valve train or cylinder head that allowed better breathing, learn something new everyday!

 

[ClutchMaster]

This was pulled from the article I posted....

“There are also pumping losses, which is the power wasted in pumping air through the engine from intake to exhaust. Up to 300 litres of air per second flows through a 1000cc engine at 18,000rpm, and a V4 crankcase layout deals with that flow much better than an inline-four crankcase, so the V4 loses less power through pumping losses.“

Someone please tell me how there’s a difference in pumping losses between an inline-4 and a V-4......I’m all ears. It’s not a two stroke, air flows through the cylinder head, not the crankcase.

 

[kinger]

@ClutchMaster its magical flashing lights duh!

 

[ClutchMaster]

@ClutchMaster its magical flashing lights duh!

Yea it’s magic!
FYI a V-4 with the modified uneven firing order makes less horsepower than an even firing order. Basically increased torque with a compromise of lower horsepower.

 

[stevewithOCD]

Ducati has a V-4 coming out that is gonna be NASTY!

Must be something to them.
The In-line 4's are getting beat pretty bad these days.

 

[ClutchMaster]

This is a big reason.......

https://en.m.wikipedia.org/wiki/Desmodromic_valve

 

[yamadoo]

This is a big reason.......

https://en.m.wikipedia.org/wiki/Desmodromic_valve

Very interesting

 

[74Nitro]

This is a big reason.......

https://en.m.wikipedia.org/wiki/Desmodromic_valve

Agree, it's why Ducati has the edge in power. Pneumatic systems are closing the gap though. Honda is extremely close to the Ducati in outright speed now.

 

[Snorunner]

I have seen parasitic drag mentioned in this posting. Good point! If you have ever turned over an in-line engine on an engine stand. By hand. Compared to a V engine. You can feel the difference. That’s why inline engines need higher cold cranking amp batteries. My Cliff Claven moment for now. Might be why inlines have more torque. More inertia once you get them moving.

 

[ClutchMaster]

I have seen parasitic drag mentioned in this posting. Good point! If you have ever turned over an in-line engine on an engine stand. By hand. Compared to a V engine. You can feel the difference. That’s why inline engines need higher cold cranking amp batteries. My Cliff Claven moment for now. Might be why inlines have more torque. More inertia once you get them moving.

Two extra main bearings to drag through the oil, but they hold big power!!

much more parasitic drank on any motor with valve springs, gas springs better, no harmonics that bust valve train at high rpm, but still more drag than a mechanical open close actuator. The biggie is the super aggressive ramp profiles you can run on the cam lobe, similar to a ultra high rate lift roller cam......but no giant springs and more area under the curve for high air flow.

 

[yamarider13]

I heard Yamaha tested V 4's for a engine to put in the vmax 4 before they decided to go with a inline because they felt the engine put out more power then they wanted.